Single crystal electron spin resonance studies of oxy(O17) cobalt myoglobin will be undertaken to determine ligand electron density and refinement of the CoO-O bond angle. Single crystal x-ray crystallography of deoxy cobalt hemoglobin is underway to determine direct comparison with the native protein. EPR as a function of pH and IHP concentration for carpHbNO will be measured. Preparation and Mossbauer spectra of 57Hb carp. Preparation and properties of Cobalt-carp hemoglobin. Preparation and properties of cobalt sickle cell hemoglobin.